M3 style side mirrors are basically M5 side mirrors. They don't look right mounted on E46. To me they look like Dumbo ears...
Only way to go is to get OEM M3 side mirrors to mount on E46. For coupes and verts they are direct bolt ons. For sedan and touring you have to modify the mirror base plates so that they line up properly. There is the Rogue Engineering DIY for this.
In either case you still need to transfer the mirror motors from your ZHP into the OEM M3 mirror housings. This does take some work and there are DIYs posted in this forum. I have one that I will be updating when I do my mirrors...
I have done this modification several times with my recent retrofit on Steve's Imola Vert ZHP. Once I get my M3 mirrors painted and base plates modded, I will transplant the mirror motors from my ZHP into the M3 mirror housings then plug everything in... there is more work you have to do on Tourings and Sedans but when completed it is well worth all the work to get them installed. At least to me it is.
The OEM M3 side mirrors look perfect mounted on any E46 :cool
https://live.staticflickr.com/5466/1...2dce4a1_5k.jpg
https://live.staticflickr.com/8762/1...e7ea67f_5k.jpg
https://live.staticflickr.com/7780/1...4bafbb2_5k.jpg
I have a friend who parts wrecked M3's and sells salvageable parts. I get my parts from him when I need them.